How Much ZzzQuil Can You Safely Take?
In our latest question and answer, our pharmacist discusses the dosing recommendations for ZzzQuil Sleep Aid.
I just purchased ZzzQuil to help me get some sleep. It says to only take one cap full but could I double dose without running into any issues? I’m about 350 lbs.
Sep 21, 2022- The recommended dose of most ZzzQuil products is 50 mg (two tablespoonfuls of liquid or two liquicaps) taken at bedtime. Doses should not exceed 50 mg as a sleep aid because higher amounts can cause a hangover effect the next morning or paradoxical reactions like insomnia. ZzzQuil Ultra tablets contain a different active ingredient and the recommended dose is just one 25 mg tablet at bedtime.
Answer
ZzzQuil Nighttime Sleep Aid is a product manufactured by Vicks in multiple formulations including:
- ZzzQuil Liquicaps
- ZzzQuil Warming Berry Liquid
- ZzzQuil Calming Vanilla Cherry Liquid
- ZzzQuil Soothing Mango Berry Alcohol-Free Liquid
- ZzzQuil Ultra Tablets
Most ZzzQuil products contain the sedating antihistamine diphenhydramine, the active ingredient in Benadryl. ZzzQuil Ultra tablets contain doxylamine (an antihistamine similar to diphenhydramine). The onset of action of both diphenhydramine and doxylamine is about 30 minutes, and the maximum sedative effects begin 1-3 hours after taking a dose. For most individuals, the duration of action ranges from 4—6 hours.
Liquid ZzzQuil Dosage Recommendations
All liquid formulations of ZzzQuil contain 25 mg of diphenhydramine per 15 ml (one tablespoon). Per the manufacturer, the recommended dose is 30 ml (two tablespoonfuls) at bedtime, which equates to 50 mg of diphenhydramine. When using diphenhydramine as a sleep aid, single doses should not exceed 50 mg per dose.
ZzzQuil Liquicaps Dosage Recommendations
Each liquicap of ZzzQuil contains 25 mg of diphenhydramine. The recommended dose at bedtime is 2 liquicaps at bedtime, for a total dose of 50 mg.
ZzzQuil Ultra Tablets Dosage Recommendations
Each tablet of ZzzQuil Ultra contains 25 mg of doxylamine. The recommended dose at bedtime is 1 tablet at bedtime, for a total dose of 25 mg.
Additional Information
In these situations, the dosage recommendation is different versus use as a sleep aid.
Doses up to 100 mg have been safely used for the treatment of allergic reactions. However, as ZzzQuil is purely indicated for use as a sleep aid, dosages should not exceed 50 mg (30 ml).
Doses above this have the risk of causing a "hangover" effect the next morning and more rarely, paradoxical reactions such as insomnia and restlessness.
References & sources
- Diphenhydramine Monograph — PubChem
- ZzzQuil Manufacturer Website — ZzzQuil.com
Glossary — Terms in This Answer
- Antihistamine
- A medication that blocks the effects of histamine in the body to reduce allergic reactions or induce drowsiness.
- Diphenhydramine
- A sedating antihistamine commonly used in over-the-counter sleep aids and allergy medications.
- Doxylamine
- An antihistamine similar to diphenhydramine that is used in some sleep aid formulations.
- Onset of action
- The amount of time it takes for a medication to begin working after being taken.
- Duration of action
- The length of time that a medication continues to produce its effects in the body.
- Formulations
- Different versions or preparations of a medication, such as tablets, liquids, or capsules.
- Paradoxical reactions
- Unexpected effects of a medication that are opposite to its intended purpose, such as insomnia from a sleep aid.
- Indicated
- Approved or recommended by a manufacturer for a specific use or medical condition.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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